Thermal Performance Examples

These thermal images were taken under ambient conditions of still air at 25°C with the components

mounted on horizontal standard test boards as defined below.

JEDEC standard circuit board:

2” (50.8mm) square FR4

2 outer power planes, 2 ounce (70μ) Cu

1” (25.4mm) square exposed

2 inner signal planes, 1 ounce (35μ) Cu

(continuous planes)

In contrast to the flat chip format, the OARS format keeps the hot spot thermally distant from the

solder j oints and reduces undesirable heat delivery into the PCB. Further thermal images for other

ohmic values and power dissipations are available on request.

Kelvin (4 Terminal) Mounting

For high precision applications a Kelvin (4

Terminal) mounting method is

recommended. An example to illustrate the

design principle is shown. High current

connections are made to the two pairs of

larger pads, whilst the voltage sense

connections are made to the two smaller

central pads.

OARS1-R005 at 2W

OARSXP-R0025 at 5W

Surface Mount

Sense Resistors

OARS, OARS-XP, OARSZ Series

11.16

General Note

TT Electronics reserves the right to make changes in product specification without notice or liability.

All information is subject to TT Electronics’ own data and is considered accurate at time of going to print.

© TT Electronics plc

http://www.ttelectronics.com/resistors

BI Technologies IRC Welwyn